How to create a low-cost, isolated, wireless Intranet

My idea is to have multiple WiFi APs all linked together wirelessly forwarding each other's traffic. As in: no Ethernet cables. There would be one exception, a small file server connected to one of the APs via Ethernet. The wireless network would have no Internet access, but would have other services available on the file server. I'm thinking of things like:- a web page or wiki, where people could list/share things- a gallery where people could up/download pictures / video- a DNS server which would redirect any DNS request to the common webserver- a XMPP chat server or IRC server which anyone could connect to

How do I get started with this?

I have a small Linux file server and three (3) Linksys WRT54g routers.

Sounds great except: why? There are already services on the internet that can do everything you mention very well. Why reinvent the wheel? Even if you want to host stuff internally you can do that without a messy wireless setup.

Also: each additional wireless access point and client device that connects to the network will cut overall performance by a bit, especially if the access points are basically dumb repeaters (as opposed to intelligent mesh routers which are tricky in their own right).

Oh, I'm going to run this in the deep woods (no Internet) during an event which will span many acres. But I thought it would be a neat idea to have a way for people to share their pictures on their phones. It's also an exercise which I thought would be fun.

If by people you mean a set of staff that is already highly motivated to use the features of such a system, I can see that they might use it a bit if the event goes for 4 or 5 days with no other recourse for internet access or whatever. If you mean random people who come and go from the event, you'll probably be lucky to see 1% uptake by the random curious person who is otherwise extremely bored.

Going to an outdoor event doesn't sound like the ideal environment to motivate me to want to learn and use a home brewed social sharing platform that will only exist or be easily accessible for a few days.

As a project for learning, there are a few interesting things there but to be honest, if you have any skill in setting up servers and stuff, those things can all be done on a single server in about 30-60 minutes. They are really common software packages and easy to setup and install. The wireless would be easy if you used good equipment like Ubiquiti Unifi radios too. Using WRT54g, you could probably just setup a few APs with the same SSID on different channels and space them around a bit. If they all have wired LAN connections between them, that is all it takes. Otherwise you could have one central AP and a star layout of other APs in client bridge mode to basically connect other wireless clients to the main IP through the surrounding APs. Nothing complicated but it will require models of the hardware that can run DD-WRT or Tomato firmware (I think tomato does the client bridge config).

The learning part could be done in a day on a server at home. If you want to do the best thing for your users, you would probably do better to just spend your effort making sure the internet is working properly so people can use their preferred platforms for stuff.

The event does go 4 to 5 days and there is a sizeable staff. And there's no real Internet to speak of. Occasionally a cell phone might get reception long enough to send a brief message out, etc.

Since I don't want to run Cat-5 all over the woods, I was thinking WiFi repeaters would be good. I don't expect to have a lot of bandwidth, but I would want people to connect their cell phones to the access points to use it. Mostly to get a map of the event or to upload pictures to a gallery (which might be shown on projectors) or to have a general message board for people to post messages to each other.

Hmm, depending on the size of the area and the number of devices you want to support at once, the WRT54G probably won't do a good job. In my experience you can get maybe 8-10 devices on one of those things at a time before you have a lot of problems, especially if there is a lot of use and using a bridged network makes that much worse.

You might want to stick with starting with a single nicer AP with a good management interface and just have a limited coverage area around the entrance or main gathering area or whatever. If you have a budget you can add more coverage but spending a bunch of time and money on setting up equipment that will just cause a frustrating experience is bound to be a disappointment.

Blue-skying here, but I'd try your WRT54Gs with DD-WRT and set up a WDS topology. I'd want to know how much area to cover and how many 54Gs were available--maybe use some as wireless bridge backbones with another connected back-to-back for AP on a different channel?

maybe use some as wireless bridge backbones with another connected back-to-back for AP on a different channel?

Ya know, this isn't a bad idea. Maybe connecting two together via a long 100m Cat-5 run to spread it out would help this work better. Anyway, thanks for the feedback guys. I think I'll get started on this asap.

I am going to assume you want directional 'trunks', (using Channels 1 and 6) and omnidirectional 'Access points' (using channel 11) I also have to assume you have 110 volt power where you want to place equipment.

You need to be careful! I started out with 4 WRT54GL's with a mix of omnis and biquads, then mixed in 2x ubiquiti nanostation loco M2's, and now I'm using 5 nanostation loco M5's (feeding consumer wireless routers), a pair of nanobridge M5's, and a rocket M5 with 19db sector with core routing by a mikrotik rb2011 and rb750 . Wireless networks are addictive!

You need to be careful! I started out with 4 WRT54GL's with a mix of omnis and biquads, then mixed in 2x ubiquiti nanostation loco M2's, and now I'm using 5 nanostation loco M5's (feeding consumer wireless routers), a pair of nanobridge M5's, and a rocket M5 with 19db sector with core routing by a mikrotik rb2011 and rb750 . Wireless networks are addictive!

Oh, I'm going to run this in the deep woods (no Internet) during an event which will span many acres. But I thought it would be a neat idea to have a way for people to share their pictures on their phones. It's also an exercise which I thought would be fun.

You're looking for something that can do mesh, but you're asking for a lot. At 2.4GHz, you're going to get a lot of loss from the trees alone. Here's an example:

Quote:

Vegetation Loss – The loss expected due to radio energy being absorbed by the moisture content of the vegetation. The loss will vary for every situation, however the typical free loss expected at different frequencies has been estimated by the International Telecommunication Union. 900 MHz 2.4 GHz 5.8 GHz Example: 150 feet of trees 9 dB 25 dB 60 dB

I can't help with the low-cost (what I work with is heavy-duty stuff), but you might want to put some thought into mounting orientation. If it's flat but densely packed with trees, horizontal polarization might be beneficial.

I'm going to assume that this mesh would have one exit, so you'd basically want to design it in a star configuration. This helps avoid any routing issues that occur. Otherwise, something along the lines of STP is a necessity (and complicates matters).

Anything you're using for PTP is going to basically require line of sight for any sort of good throughput. Ubiquiti is a good manufacturer (and would be more solid than the Raspberry Pi solution), but you have the problem of being in the same ISM band as the WiFi will be (2.4 GHz). If you were to choose 5.8 GHz, you'd limit the type of devices (and range) that could connect. If you went with 5.8 GHz for backhaul, you'd need a really clear path.

STANDARD DISCLAIMER: Depending on the country, both output power AND EIRP may be restricted further than US standards. If you create a system yourself, you must ensure that you comply with FCC/applicable regulations for emissions. For US-based systems, utilize http://www.afar.net/tutorials/fcc-rules but verify with FCC Part 15 to ensure compliance.

You need to be careful! I started out with 4 WRT54GL's with a mix of omnis and biquads, then mixed in 2x ubiquiti nanostation loco M2's, and now I'm using 5 nanostation loco M5's (feeding consumer wireless routers), a pair of nanobridge M5's, and a rocket M5 with 19db sector with core routing by a mikrotik rb2011 and rb750 . Wireless networks are addictive!

Lol. what?

Basically I bought enough gear to start a small WISP, and used it to build a meshnet:

It's more than a $1000 worth of gear, but for 40-150mbps of aggregate throughput from any point to another on the network, and the cost split up between a couple people it's really a tremendous value.

I built exactly the network you described using the WRT54G's, and got between 1 - 5 mbps throughput. That could be enough for what you want to do, so don't get discouraged that you don't have 5.8 ghz ubiquiti unit's to provide point to point backhaul vs the proposed repeated setup. Just because repeating isn't ideal doesn't mean it can't be used, or that you can't reconfigure the gear later to scale up further.

I'm having difficulty locating the ddwrt-olsrd firmware. My Google-fu is seriously weak, apparently. I also found out about something called "FreiFunk" (a German revision of ddwrt-olsrd firmware), but again, can't locate the firmware to download it.

12v lead-acid batteries. The APs appear to draw a max of 500ma/h (according to the PSUs), though I haven't taken any measurements yet, so it might be less.

Darn the Ubiquiti gear uses 24 volts

Shouldn't stop you. Either a second battery or a transformer can bring you up to 24V easily (and you're going to want something in between your equipment and the battery anyways, because a "12V" lead-acid battery will actually output 12V for approximately none of its discarge cycle).

12v lead-acid batteries. The APs appear to draw a max of 500ma/h (according to the PSUs), though I haven't taken any measurements yet, so it might be less.

Darn the Ubiquiti gear uses 24 volts

Shouldn't stop you. Either a second battery or a transformer can bring you up to 24V easily (and you're going to want something in between your equipment and the battery anyways, because a "12V" lead-acid battery will actually output 12V for approximately none of its discarge cycle).

The OP was dreaming this would be low cost, every barrier he puts up, increases costs.

12v lead-acid batteries. The APs appear to draw a max of 500ma/h (according to the PSUs), though I haven't taken any measurements yet, so it might be less.

Darn the Ubiquiti gear uses 24 volts

Shouldn't stop you. Either a second battery or a transformer can bring you up to 24V easily (and you're going to want something in between your equipment and the battery anyways, because a "12V" lead-acid battery will actually output 12V for approximately none of its discarge cycle).

The OP was dreaming this would be low cost, every barrier he puts up, increases costs.

Hey, you're the one who suggested a few hundred dollars worth of professional networking equipment when the OP was asking for suggestions on how to use a few (existing) cheap consumer-grade routers.

Just giving the OP options. And he may find he needs something along those lines anyways (even with the equipment he has), depending on how tolerant the power supply in the WRT54G is of under/overvoltage.

Your all barking up the wrong tree, trying to build an enterprise network in the woods. WDS, and OLSRd are not the sort of solutions you are looking for.

Look at the various projects dealing with emergency/cutoff wifi like Byzantium linux, Commotion Wireless, or PirateBoxes. People have been working on the exact scenario you are describing and have come up with a ton of solutions. People have run almost everytype of cut off service from dropbox clones, offline twitter, to even some Cell Networks.

I was wondering about this, too. Is there a Linux daemon that can masquerade as a Twitter server? That would be cool.

Quote:

because a "12V" lead-acid battery will actually output 12V for approximately none of its discarge cycle

A lead-acid battery typically starts at 12.7v and eventually discharges to 11.7 when it is nearly depleted. So it turns out that a lead-acid battery is within +/-5% of 12v for almost the entire 0time. As for the WRT54g routers, apparently they're quite tolerant of voltage ranges. Most models use unregulated 12v power supplies which means the on-board electronics have to handle a good range of voltage. I read somewhere that it is as wide as 9v to 17v, but I can't find the source any more. (yeah, yeah. I'm looking for it.)

Your all barking up the wrong tree, trying to build an enterprise network in the woods. WDS, and OLSRd are not the sort of solutions you are looking for.

Look at the various projects dealing with emergency/cutoff wifi like Byzantium linux, Commotion Wireless, or PirateBoxes. People have been working on the exact scenario you are describing and have come up with a ton of solutions. People have run almost everytype of cut off service from dropbox clones, offline twitter, to even some Cell Networks.

For now I suggest sticking a to a fully bridged setup, and ignore olsrd until you are looking to refactor your network with a loop or true mesh topology.

If the routers are all the same, that is to say all based on broadcom you might use WDS, setting them all as peers to each other. This way you keep the same SSID throughout. Or you can set them in repeater mode, changing the SSID on each hop. This is a good way to remind yourself to connect to the furthest upstream unit.

I'm going to post the WDS configuration as it seems like it matches your needs best right now:

IP/DHCP on master unit, DHCP is on here, and the DNS is pointed at the router to allow use of dnsmasq

IP/DHCP for downstream unit, DHCP is disabled here

Wireless setting for all, just simple and straightforward. You'll likely want to check that the encryption is disabled.

WDS setting, here you place the wireless mac addresses for all the unit's you will have participating

Services > Services - This entry here resolves all DNS requests to 10.10.10.50, which could be your web server

My only question regarding this is: Does this type of setup (OLSRd) allow one to move between access points? (will the APs know how to hand off as you move out of range of one and into the range of another?)

I don't see it as being feasible to have a single SSID with roaming when doing an OLSRD setup, as each AP should have a different subnet. It could in theory be possible using DHCP authoritative to coax things along, but it just seems like it depends way too much on the client doing the right thing.

I don't see you getting a performance increase here with just the WRT54G's and olsrd. It's not so much a performance tool as a scaling tool to allow you to grow your network with multiple paths (for redundancy), and to allow some level of IP portability.

3 mbps sounds reasonable for a network repeated twice. Adding a cable or a pair of dedicated wireless unit's would be the best way to boost performance.

Though I will give you one thing to try on your existing setup, tune the fragmentation threshold downward to around 500 (in advanced wireless). This helps with the huge collision domain that exists with a multiply repeated network.